Ti and Zr complexes of ferrocenyl amidinates

Abstract

Preparation of a N-ferrocenyl-amidinate complex was achieved by employing (TMEDA)Li[(CpFeC(5)H(4))NC(Ph)NSiMe(3)] (1) to prepare Cp*Zr[(CpFeC(5)H(4))NC(Ph)NSiMe(3)]Cl(2) (2). Complex 2 exhibited poor polymerization activity and thus a series of C-ferrocenyl bis(amidinate) complexes of the type M(L)(2)Cl(2) (M = Zr, 4; M = Ti, 5; L = (CyNC(CpFeC(5)H(4))NCy) were synthesized via reaction of ferrocenyl-amidine, H(L) and M(NMe(2))(2)Cl(2) (M = Ti, Zr·2THF). Half sandwich mono(amidinate) complexes, Cp'ZrLCl(2) (Cp' = Cp, 7; Cp' = Cp*, 8), were prepared by the reaction of Cp'ZrCl(3) with Li(L) and subsequently alkylated to give M(L)(2)Me(2) (M = Zr, 9; M = Ti, 11), CpZr(L)(CH(2)Ph)(2) (12) and Cp*Zr(L)Me(2) (10) with the appropriate alkylating agent. Abstraction of a methyl group from 7 with B(C(6)F(5))(3) and [Ph(3)C][B(C(6)F(5))(4)] proceeded cleanly to give [{CyNC(CpFeC(5)H(4))NCy}(2)ZrMe][MeB(C(6)F(5))(3)] 13 and [{CyNC(CpFeC(5)H(4))NCy}(2)ZrMe][B(C(6)F(5))(4)] 14, respectively. Similarly, the analogous CpZr and Cp*Zr derivatives LZr{CyNC(CpFeC(5)H(4))NCy}CH(2)Ph] [PhCH(2)B(C(6)F(5))(3)] L = Cp 15, Cp* 17 and [LZr{CyNC(CpFeC(5)H(4))NCy}CH(2)Ph][B(C(6)F(5))(4)] L = Cp 16, Cp* 18 were prepared. Cyclic voltammetry studies on the metal complexes containing ferrocenyl-amidinates reveal quasi reversible oxidation and reduction waves for the ferrocene/ferrocenium couple. The dichloride complexes (4-8) activated with MAO and dialkyl complexes (9,10) activated with B(C(6)F(5))(3) and [Ph(3)C][B(C(6)F(5))(4)] showed low ethylene polymerization activities.